Stock material or miscellaneous articles – All metal or with adjacent metals – Laterally noncoextensive components
Reexamination Certificate
2001-10-24
2003-04-15
Dunn, Tom (Department: 1725)
Stock material or miscellaneous articles
All metal or with adjacent metals
Laterally noncoextensive components
C428S606000, C420S557000, C420S901000, C505S230000
Reexamination Certificate
active
06548187
ABSTRACT:
This application is based on Application No. 2001-121195, filed in Japan on Apr. 19, 2001, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a Sn based alloy containing a Sn—Ti compound that is used for manufacturing a Nb
3
Sn superconducting wire by an internal diffusion method, and a method for manufacturing the same. The present invention also relates to a precursor of the Nb
3
Sn superconducting wire using the Sn based alloy.
2. Description of the Related Art
A method using a Nb
3
Sn compound prepared by an internal diffusion method has been proposed for manufacturing superconducting wire. In the internal diffusion method, a precursor of the Nb
3
Sn superconducting wire called a module is prepared by integrating a metallic Sn rod at the center of a Cu base metal in which a number of metallic Nb rods are integrated so that they do not make direct contact with each other. The module is heated at about 650° C. and drawn so that Sn reacts with metallic Nb by heat diffusion of the Sn to finally obtain the Nb
3
Sn wire useful as a superconducting wire material. For improving the superconductive characteristics of the Nb
3
Sn superconducting wire, prepared by the internal diffusion method, in a high magnetic field, a Sn based alloy containing a Sn—Ti compound is prepared by adding Ti into the Sn base metal. It is known in the art that this Sn based alloy has better superconducting properties than Nb
3
Sn wire using metallic Sn. However, the Sn based alloy containing the Sn—Ti compound as used herein involves the problem of generating defects due to the mingling of non-molten Ti and Ti oxide into the Sn based alloy during the conventional melt-casting process, because the difference between the melting points of Sn (232° C.) and Ti (1670° C.) is substantially large for manufacturing the Sn base containing Ti, and Ti is liable to be oxidized during the process.
A proposed method for manufacturing a defect-free Sn based alloy containing the Sn—Ti compound comprises, for example, melting Sn by heating at 600 to 1750° C. under an inert gas atmosphere, adding 0.3 to 6.5% by weight of Ti relative to the content of Sn, and casting the mixture into a mold made of cast iron or stainless steel at 500 to 1750° C. (Japanese Patent Publication No. 6-76625).
However, since the Sn—Ti compound is not finely dispersed in the Sn based alloy which was melted under an inert gas atmosphere and cast by using the cast iron or stainless steel mold, improved superconductive characteristics cannot be expected. In addition, since the Sn based alloy containing the Sn—Ti compound produces so large shrinkage cavity, manufacturing yield of the Sn based alloy containing the Sn—Ti compound becomes poor. Therefore, some improvements have been desired in the method for manufacturing the Sn based alloy containing the Sn—Ti compound.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method to solve the above problems in the conventional manufacturing methods. A further object of the present invention is to provide a Sn based alloy containing a Sn—Ti compound in which granules of the Sn—Ti compound having a fine particle diameter are uniformly dispersed where permitting the cast ingot to be free from forming the shrinkage cavity, as well as a method for manufacturing the Sn based alloy containing the Sn—Ti compound uniformly dispersed therein.
The present invention provides a Sn based alloy containing a Sn—Ti compound prepared by adding 0.1 to 5% by weight of Ti relative to the content of Sn, wherein the particles of the Sn—Ti compound have a maximum diameter of 30 &mgr;m or less and a mean diameter of within a range of 5 to 20 &mgr;m.
The present invention also provides a method for manufacturing a Sn based alloy containing a Sn—Ti compound finely dispersed therein, comprising the steps of melting Sn by heating at 1300 to 1500° C. in vacuum or under an inert gas atmosphere, adding 0.1 to 5% by weight of Ti relative to the content of Sn followed by melting the mixture by heating at 1300 to 1500° C., and casting the molten liquid into a mold made of copper.
The present invention further provides a method for manufacturing a Sn based alloy containing a Sn—Ti compound finely dispersed therein, comprising the steps of melting Sn by heating at 1300 to 1500° C. in vacuum or under an inert gas atmosphere, adding 0.1 to 5% by weight of Ti relative to the content of Sn followed by melting the mixture by heating at 1300 to 1500° C., and casting the molten liquid into a mold made of copper through a carbon pouring cup mounted on the copper mold.
The present invention further provides a precursor of a Nb
3
Sn superconducting wire having a structure in which a number of the Nb metal materials and Sn based alloys containing the finely dispersed Sn—Ti compound are integrated in a copper based metal so that they do not make direct contact with each other.
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Egawa Kunihiko
Kubo Yoshio
Nagai Takayuki
Taguchi Osamu
Cooke Colleen P.
Dunn Tom
Leydig , Voit & Mayer, Ltd.
Mitsubishi Denki & Kabushiki Kaisha
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